Changes like this go nowhere, then happen rapidly.
Price is too high, features too few, distinct advantages under compelling, and ergonomics too nomic ... until they aren't.
In other words, its a big change of form and function, not to mention the physics tradeoffs of these products, so it makes sense that the right combo is taking a while to fall into place.
If Apple customers, who have the shiny shells to shell out, fall in love with their devices, that will mean a lot.
Commercial consumer VR has been available for the better part of a decade now and this doesn't seem even close to happening.